1. Field of the Invention
The present invention is generally in the field of electrical circuits. More particularly, the invention is in the field of voltage up-conversion circuits.
2. Related Art
Portable and mobile electronic devices, such as wireless communication devices, typically include analog and digital systems that require multiple operating voltages. The multiple operating voltages required by analog and digital systems are typically provided by on-chip DC-DC voltage converters, which can utilize a single external voltage source, such as a battery. However, battery voltage can drop significantly below 5 volts, which is a required operating voltage for some system interface circuits. As a result, analog and digital systems in portable and mobile electronic devices typically require on-chip voltage up-conversion.
Voltage up-conversion is typically provided by using switching regulators, such as a Cuk converters, or switched-capacitor or charge pump converters. However, both of these approaches typically require high voltage transistors, such as 5 volt transistors, to handle high output voltage. However, current technologies used for fabrication of semiconductor dies for core logic, analog, and I/O circuits typically provide transistors that operate at significantly lower voltages than 5 volts. Although 5 volt transistors can be added for a voltage up-conversion circuit in the fabrication process, adding 5 volt transistors increases fabrication process complexity, which increases manufacturing cost. In another approach, a separate semiconductor die can be fabricated using a 5 volt process for a voltage up-conversion circuit. However, this approach undesirably increases system integration complexity and system cost.
Thus, there is a need in the art for a low cost voltage up-conversion circuit for analog and digital systems in portable and mobile electronic devices, such as wireless communication devices.